The renin-angiotensin-aldosterone system and the prostaglandins are important determinants in the regulation of blood pressure and salt and water balance. Angiotensin II, by contracting vascular smooth muscle and stimulating aldosterone and prostaglandin synthesis, occupies a central role in these control mechanisms. Recently, two other angiotensins, (des-AspI) angiotensin I and (des-AspI) angiotensin II, were found to have actions qualitatively similar to angiotensin II. In view of these findings, the vascular and adrenal roles of these three angiotensins require further characterization in states of altered sodium balance, altered potassium balance, and experimental secondary hyperaldosteronism. Angiotensin II has been found to stimulate prostaglandin synthesis in many tissues; however, its action on intra-adrenal prostaglandin synthesis has been neglected. This possibility may be important since prostaglandin E stimulates aldosterone biosynthesis as well as augmenting angiotensin-induced aldosterone synthesis. Thus, intra-adrenal prostaglandins may mediate a component of the basal and angiotensin-mediated steroidogenesis. The research proposal will characterize in vivo and in vitro the vascular and adrenal actions of angiotensin I, angiotensin II, and their des-aspartyl metabolites in states of normal and altered sodium and potassium balance and experimental secondary hyperaldosteronism. Secondly, the intra-adrenal role of prostaglandins and their interactions with the angiotensins in the control of steroidogenesis will be determined in normal and altered states of sodium and potassium balance. Finally, the site of angiotensin and prostaglandin stimulation of aldosterone biosynthesis will be determined in vivo. By furthering our understanding of these normal control mechanisms, we hope to better understand the involvement of these two hormonal systems in hypertensive and edematous conditions.